Tension release for sewing machines



Sept. 15, 1931.

N. v. CHRISTENSEN TENSL'ON RELEASE FOR SEWING MACHINES Filed Aug. 31, 1/928 3 Sheets-Sheet l Ill!!! llll Sept. 15, 1931. N. v. CHRISTENSEN TENSION RELEASE FOR SEWlNG MACHINES Filed Aug. 31, 1928 3 Sheets-Sheet 2 R mfi M I b m w as NE WM N MW 1% m N Q Q \N QN hw' N N N .W A M. ww i V E .1 W N N 1 u Nm. mm Q \W %M 1 I 1 .w% R Qw.

S 'p 1931. N. v. CHRISTENSEN 1,823,817

TENSION RELEASE FOR SEWING MACHINES Filed Aug. (51, 1928 3 Sheets-Sheet 3 6cm mu Patented Sept. 15, 1931 UNITED STATES PATENT FFICE NORMAN V. CHRISTENSEN,

OF CHICAGO, ILLINOIS, ASSIGNOR TO UNION SPECIAL MA- TENSION RELEASE FOR SEWING MACHINES Application filed August 31, 1928. Serial No. 303.282.

The invention relates to new and useful improvements in tension releasing mechanism for sewing machines, and more particularly to a tension releasing mechanism for a plurality of needle threads and a plurality of looper threads, whereby all tension on the threads of the machine may be releasedwhen the presser foot is raised.

An object of the invention is to provide a tension releasing mechanism of the above character wherein plates independently associated with the tensions for the needle threads and the tensions for the looper threads may be simultaneously actuated for releasing all of the tensions.

A further object of the invention is to provide a tension releasing mechanism of the above type wherein the tension releasing plates are moved vertically in an upward direction for releasing the tensions by an oscillating shaft which receives its movement from the device for lifting the presser foot.

in the drawings which show by way of illustration one embodiment of the invention 2* Fig. 1 is a view partly in section and partly in plan of the standard and overhanging arm of a sewing machine with the improvements applied thereto.

Fig. 2 is a vertical sectional View laterally of the standard, all of the parts being omitted except the tension releasing mechanism.

Fig. 3 is a view partly in front elevation and partly in section of a portion of the machine showing the tension releasing mecha nism for the needle threads.

The machine is provided with a standard and an overhanging arm and with separate tensions for two needle threads and also separate tensions for two looper threads. The needle thread tensions are at the front side of the standard and the looper thread tensions are at the rear of the standard. Associated with the needle thread tensions is a releasing plate which is provided with means for separating the tension discs for releasing the tension on the threads when the plate is raised. There is a similar plate for the looper threads. These plates are simultaneously lifted by a rock shaft having arms connected to the plates for raising and lowering the plates when the rock shaft is oscillated in one direction or the other. The rock shaft is provided with an arm and a link connection between the arm and the lever which raises the presser bar. hen the presser bar is raised this rock shaft is oscillated and it will in turn raise the releasing plates which will separate the tensions and release all tension on all threads.

Referring more in detail to the drawings, the invention is shown as applied to a machine having a standard 1 carrying an overhanging arm 2. Both the standard and the arm are hollow. The needle bar is mounted at the outer end of this overhanging arm and is actuated by a lever located within the arm. The presser foot is carried by a presser bar This presser bar 3 is moved downward to cause the presser foot to engage the material by a spring 4 mounted on a lug 5 and tensioned by suitable means engaging the leaf spring intermediate its ends. The free end of this spring bears on an arm 6 carried by a collarattached to the presser bar. The presser bar is raised by means of a lever 7 which is pivoted at 8 to the overhanging arm. The free end of this lever extends underneath the arm 6. The lever is provided with an extension 9 which is bent so as to extend outwardly through an opening 10 in the stamiard. At the outer end of this lever there is an eye 11 to which a suitable flexible member is connected and the flexible member may be connected to either a treadle or a knee shift, thus providing means whereby the presser bar, may be readily raised.

Besides the leaf spring there is the usual coil spring attached to the end of the lever 7 and the head of the machine for depressing the free end of the lever when released from the knee shift or treadle control means, thus moving the end of the lever out of engagement with the arm (3 when the presser foot is on the material.

Mounted on the front face of the standard 1 are two tensions 12, 12. Only one of the e tensions is shown in Fig. 3. The tensions are all alike. Each tension consists of two discs 13 and 14. A post 15 is threaded into the standard and these tension discs are freely mounted on this post. It is understood that there is a post for each pair of tension discs. There are two pairs of tension discs for the two needle threads respectively and also two pairs of tension discs for the two looper threads. Said latter tension discs are mounted on the rear face of the standard. Each post is provided with a shoulder 17. Mounted on the post before it is attached to the overhanging arm is a sleeve 18. This sleeve 18 bears against the shoulder and is thus held from endwise movement on the post. The sleeve is provided with an enlarged portion 19. The tension discs bear against this enlarged portion on the sleeve. Surrounding the post is a coil spring 20. A nut 21 is threaded onto the end of the post. A sleeve surrounds the post and is provided with an abutment which engages the spring 20. The nut bears against this sleeve and thus puts the spring under tension. By turning the nut the tension of the spring can be varied.

The spring at its inner end bears against the tension disc 13. The thread runs between the tension discs and thus it is that a tension is placed on the threads. These tension discs and the means for putting the threads under tension form no part of the present invention, except in combination with the means utilized for releasing the tension on the threads. There is a plate secured to the standard 0 l the machine by the tension post, and this plate is provided With projecting arms 23 and 24c, there being a pair of arms associated with each of the tensions. These arms are formed with thread eyes 25 and 26 respectively. The needle threads are indicated at n in Fig. 3. These needle threads pass from the supply through the thread eyes 26, then between the tension discs, and thence through the thread eyes There are similar thread guiding eyes associated with the tensions for the looper threads on the rear face of the arm.

Associated with each pair of tensions is a releasing plate 2. This relea-ing plate 27 is provided with two slots 28, The sleeve 18 has a reduced portion extending through the slot in the plate associated therewith and the enlarged portion 19 on the sleeve 18 overlies the sides of the slot and serves as}. a guid ing means for the plate. The plate can be freely raised and lowered, sliding vertically on the tension posts. The plate is provided with a pair of tension releasing arms 29 for each tension. These arms project outwardly from the plate and thence verticalhx, and the upper end of each arm is V-shaped or wedge-shaped. The arms are so positioned that when the plate is raised, these wedgeshaped ends of the arms will pass between the tension discs and separate the same. By providing two spaced arms located on opposite sides of a vertical line passing through the center of the disc there is a positive separation of the tension discs at the portions thereof between which the thread pases. In other words, there is no rocking of the tension disc so as to release the thread at one side of the tension disc and clamp it at the other, as occurs when there is a single arm utilized for separating the discs.

There is a tension realising plate tor the tensions controlling the looper threads which is similar in construction to t 1e tension releasing plate shown in Fig. 3 which operates to release the tension on the needle threads. At the lower end of this tension releasing plate there are two notches 210, 30. These notches are similar in construction. Only one notch is utilized in connection with the assembling of the plates. The purpose of the second notch is to make the plates at the front and rear of the machine reversible.

The plates are raised and lowered by means of a rock shaft 31. The rock shaft Ill carries two arms 32 and 33. vEach arm provided with a stud 34 (see Fig. This stud engages the notch 30 in the plate with which s a;- sociated. Then the rock shaft is oscillated in a clockwise direction, as viewed in Fig. 3, the plate will be lifted and the wedge-shaped ends of the arms 29 will pass between the tension discs, separating the discs and releasing the tension on all threads,as both plates are siniultaneously raised. lVhen the rock shaft is moved in a counterclockwise direction, then both plates will be lowered and the arms withdrawn from between the tension discs, thus restoring the tension on the threads.

Mounted on the rock shaft 31 is a sleeve 35. This sleeve 35 has an arm 36 projecting therefrom. A link 37 joins this arm 36 to a depending extension member 38 attached to the presser bar lifting lever T by suitable bolts 39, 39.

From the above it will be apparent that tensions have been provided tor the needle threads and looper threads with which are associated independent controlling plates These controlling plates are sin'iultaneously raised and lowered by a rock shaft connection with the presser bar littin g lever. lVhen the presser foot is raised through the depressing of the lever 7 then the rock shaft will release all ten be oscillated so as to sion on all the threads and when. the pressure bar lifting lever is released the free end thereof will be moved down 'ard and this will oscillate the rock shaft so as to withdraw the arms from between the tensions and thus restore all tensions on all threads.

\Vhile there has been sho vn two tensions operating independently upon two needle threads, and two tensions operating independently upon two looper threads. it will be understood, of course, that the machine may be provided with any desired number of needles or with any desired number of loopers and the proper tensions will be added for these additional threads. All of the needle thread tensions will, of course, be on one side of the standard and controlled by one control plate, while the looper thread tensions will be on the other side of the standard and controlled by the other control plate. lVhile the tensions have been disclosed as grouped on opposite sides of the standard, it is apparent that they may be otherwise grouped. It is desirable, however, that all of the needle thread tensions be controlled by one plate and all of the looper thread tensions controlled by another.

It is obvious that minor changes in the details of construction and the arrangement of parts may be made without departing from the spirit of the invention as set forth in the appended claims.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent, is:-

1. In a sewing machine the combination of a series of tensions for the needle threads, a series of tensions for the looper threads. a tension releasing plate associated with the tensions for the needle threads, a tension releasing plate associated with the tensions for the looper threads, means for supporting the respective plates whereby they may be moved vertically, a rock shaft connected to each plate, a presser foot lifting mechanism, means for connecting said rock shaft to the presser foot lifting mechanism whereby when the presser foot is lifted, the releasing plates are actuated for releasing the tensions on all threads.

In a sewing machine the combination of a hollow standard. a hollow arm carried by the standard, a presser foot lifting lever lo cated within the hollow arm and standard, tension devices for the needle threads at the front of the standard, and tension devices for the loop-er threads at the rear of the standard. and means for simultaneously releasing the tension on all threads including a rock shaft: connected to the presser foot lifti ng lever and extending through the standard from front to rear thereof.

In a sewing machine the combination of a hollow standard, a hollow arm carried by the standard, a presser foot lifting lever located within the hollow arm and standard, tension devices for the needle threads at the front of the standard, a tension releasing plate, associated with said tension devices, tension devices for the looper threads at the rear of the standard, a tension releasing plate for said last-named tension devices, a rock shaft extending through the standard from front to rear thereof, said rock shaft having arms connected to said plates for raising and lowering the same to release and restore the tensions on all the threads, and means within the standard connected to the presser foot lifting lever for oscillating the rock shaft.

4. In a sewing machine the combination of a hollow standard, a hollow arm carried by the standard, a presser foot lifting lever located within the hollow arm and standard, tension devices for the needle threads at the front of the standard, a tension releasing plate associated with said tension devices, tension devices for the looper threads at the rear of the standard. a tension releasing plate for said last-named tension devices, a rock shaft extending through the standard from front to rear thereof, said rock shaft having arms connected to said plates for raising and lowering the same to release and restore the tensions on all the threads, means within the standard connected to the presser foot lifting lever for oscillating the rock shaft, each tension device including a pair of tension discs and each tension plate having a pair of arms associated with each tension device. said arms being disposed beneath the tension device with which they are associ ated, and having wedge-shaped ends adapted to pass between the tension discs when the releasing plates are raised.

In a thread tensioning n'iechanism the combination of a support and tension device includii'ig a post mounted on said support, a mei'nber movably secured to said support by said post, devices for moving said member, and means carried by said member for rendering said tension device ineffective when said member is moved in one direction.

6. In a thread tensioning mechanism the combination of a support, a plurality of tension devices each including a post mounted on said support, a member movablv secured to said support by said posts. means for 1noving said nien'iber, and devices carried by said member for rendering said tension devices inetl'ective when said member is moved in one direction.

In testimony wh reof, I atiix my signature.

NORMAN V. CHRISTENSEN. 

